Based on the answers provided, the following corrections need to be made to the 3D object:

1. Change the base of the object from a cylinder to a hexagon. 
2. On top of the hexagon, add a cylinder that is slightly smaller than the hexagon.
3. Ensure that the height of the cylinder is half the height of the hexagon. 

Please note that the object should still be extruded in one dimension, as this aspect of the design is correct.